Helicopters are wonderful machines that, like a bumblebee, are supposed to be unable to fly. It’s all that whirling hardware linked by shafts, masts, transmissions, cyclics and collectives that give them their amazing capabilities.

But all that complication also renders them vulnerable to mechanical breakdowns, or a lucky shot, in a way that fixed aircraft – always moving, never hovering – are not. We don’t know yet what brought down a UH-60 Black Hawk early Thursday in southern Afghanistan, killing 11, including seven U.S. troops. But U.S. military officials believe the Taliban may have got off one of those deadly, lucky shots.

Battleland has written before why chopper flights in Afghanistan can be so lethal. Experts weighed in on the topic in the summer 2009 issue of Aircraft Survivability, published by the Pentagon’s Joint Aircraft Survivability Office. “Historically, aircraft combat survivability design metrics and evaluations have focused on what happens to the aircraft,” it pointed out, “with only limited consideration given to casualties generated during combat-induced aircraft damage or loss.”

The article went on to detail some key findings arrived at by experts in the field during an aircraft-casualty workshop:

— Most of the occupant injuries and fatalities appear to have occurred as a subsequent, indirect result of the crash—not as a result of direct threat effects wounding the occupants.

— A high percentage of helicopter shoot-down events are survivable. Even helicopter shoot-downs by man-portable air-defense systems (MANPADS) missiles are sometimes survivable.

— Aircraft having design features such as fire protection, energy absorbing seats, and the ability to maintain sufficient internal space for the crew/passengers after a crash from being injured by collapsing massive overhead components (e.g., rotors and gearboxes) can make a significant difference in crash survival rates.

— Passengers make up a majority of aircraft occupant losses in Operation Iraqi Freedom (OIF) and Operation Enduring Freedom (OEF).

— Rotary wing aircraft have significantly increased their gross weight since the original airframes were tested for crashworthiness, and even then, some of the aircraft did not pass the existing standards.

— Aircraft survivability evaluations and vulnerability testing have historically focused on the loss of the aircraft or its mission, and not on occupant casualties.

— Although many of the steps taken to save the aircraft can also save the occupants, attention also should be paid to saving the occupants even when the aircraft is lost.

Something to think about on this sad day for those aboard that Black Hawk..